1. Skip to navigation
  2. Skip to content
  3. Skip to sidebar




Solid Hull

Home Forums Archive Structure Designs Solid Hull

This topic contains 4 replies, has 4 voices, and was last updated by Avatar of goedjn goedjn 3 years, 11 months ago.

Viewing 5 posts - 1 through 5 (of 5 total)
  • Author
    Posts
  • #1342
    Avatar of elspru
    elspru
    Participant

    seashells don’t use reinforcement,

    simply relying on the power of geometry,

    otherwise having solid calcium carbonate.

    perhaps we can do likewise,

    and have solid hulled concrete boats.

    has anyone tried or seen examples of attempts?

    #11300
    Avatar of Carl-Pålsson
    Carl-Pålsson
    Participant

    There are two-thousand year old unreinforced concrete structures still standing, so I am sure it is possible.

    The question is why. Throwing in a couple of rebars is a pretty cheap way to dramatically improve the tensile strength of concrete.

    You could try something like a sphere or a dome I guess. But I’d guess that it will always end up both more expensive and worse performing than the same thing with reinforcement.

    #11303
    Avatar of elspru
    elspru
    Participant

    Carl wrote:

    There are two-thousand year old unreinforced concrete structures still standing, so I am sure it is possible.

    The question is why. Throwing in a couple of rebars is a pretty cheap way to dramatically improve the tensile strength of concrete.

    rebar also reduces life-expectancy of the structure, due to expansion,

    also if using rebar to keep it dry the hull must be made much thicker.

    Also with a boat, or especially submarinie the main pressure is compressive,

    since the force tends to be equivalent all around the boat.

    You could try something like a sphere or a dome I guess.

    I was thinking it in the shape of a boat,

    with making sure all sides are connected with greater than 90 degree incidence.

    But I’d guess that it will always end up both more expensive

    er no, since it’s fewer materials it’s cheaper.

    Also my idea was to make it less labour intensive,

    for instance we could have a bunch of flat surfaces,

    these flat surfaces could be cast on the ground,

    perhaps with some plastic reincorcement material,

    then the surfaces can be assembled together,

    to make the final boat.

    overall it’s easier since no plastering required (only casting),

    and the molds are very simple and flat,

    so could be done with basic materials.

    and worse performing

    you just mentoned the long-lived nature,

    thereby there are better performance attrbutes.

    than the same thing with reinforcement.

    Many ferro-cement structures, like highways and subways,

    I often look and find exposed rebar rusting away.

    If we had purer iron like of the delhi pillar perhaps it wouldn’t be an issue,

    unfortunately most iron available on the market isn’t nearly that pure,

    and i don’t currently have a furnace to make my own.

    so I’ll make some models,

    from cardboard then clay then concrete.

    calm aware desire choice love express intuit move

    #11306
    Avatar of J.L.-Frusha
    J.L.-Frusha
    Participant

    Highway Ferrocement is often exposed to harsh de-icing, impact damage and other chemicals. It’s not the rebar that’s the problem, it’s the porosity of the cement. That’s why I started the thread on waterproofing ferrocement hulls.

    Using a deeper section, to increase the distance of the rebar, from the surface, has limited value, since salt is so chemically active. Plastics are of less use, since they don’t bond as well. Oil, as an add-mixture is of even less value, since it weakens the cementation, by not bonding with the cement at all.

    So far, for ferrocement structures, the best ideas have been Hot-Dip-Galvanized rebar and sealing all of the surfaces.

    Later,

    J.L.F.

    Never be afraid to try something new…

    Remember, amateurs built the ark, professionals built the Titanic.

    #11487
    Avatar of goedjn
    goedjn
    Participant

    Also, a great deal of modern engineering is centered around making things that are just barely adequate, over their design life. buildings from antiquity (at least, the surviving ones) are seriously overbuilt. And in many cases they’ve had periodic maintenence. You can overbuild using modern techniques, too. In fact, since your life depends on it, I recommend that you do. But you’re still going to have to do maintenence. It’s not like the island you’re trying to imitate lasts forever, either. So it might be worth taking the effort to move your design from 80% impervious to 95% impervious, and devote it instead to making it 80% impervious and fairly easy to repair at sea.

    “Remember, amateurs built the ark, professionals built the Titanic.”

    Of course, the Titanic’s hull floated for about 11 months, and the Ark for a bit over 7….

Viewing 5 posts - 1 through 5 (of 5 total)

The forum ‘Structure Designs’ is closed to new topics and replies.



Posted on at

Categories:

Written by

Blog/Newsletter

Donate